Flow control valves can be used in numerous applications. In some types of flow control valves, performance is at least partially determined by the valve's ability to reliably produce a desired flow-through volume when subjected to a particular pressure difference or range of pressure differences.
One type of low-cost valve for flow control is described in U.S. Pat. Nos. 249,557, 3,990,471 and 5,117,871. Such valves, which may use linear force springs, typically limit their function to check valves, or back-flow prevention valves. Specifically, the need to characterize a rate of flow with respect to a sensible quantity such as pressure, temperature, humidity, displacement or chemical potential typically involves valves having a more complex fabrication, higher cost, and/or feedback control systems.
Therefore, in one aspect of this disclosure, a flow control valve includes a valve element and a support element, where the valve element is configured to deflect responsive to a change in pressure difference across the valve element. The support element cooperates with the valve element to present an effective flow-through area that changes as the valve element deflects. The amount of relative engagement between the valve element and the support element changes as the valve element deflects.
In this way, it is possible to obtain variable spring response depending on the amount of relative engagement. Thus, desired manufacturing costs and/or complexity may be achieved while still providing the ability for improved flow control accuracy, if desired. In one specific example, a non-linear spring system may be used to balance non-linear pressure forces, allowing it to regulate specified flow requirements.
In another specific example, a flow control valve may be used as a positive crankcase ventilation valve, which is an emissions control device that can route burned and unburned crankcase blowby gasses from the crankcase to an engine's intake manifold where the gasses can be burned. Besides reducing crankcase emissions, the recirculation of air through the crankcase can help remove moisture, and dilute NOx which otherwise could cause sludge to form. Thus a crankcase ventilation valve can extend the life of the oil and engine, in addition to reducing undesirable emissions.
According to another aspect of this disclosure, a crankcase ventilation flow control valve includes a valve element and a support element, where the valve element is configured to deflect responsive to a change in pressure difference across the valve element. The support element cooperates with the valve element to present an effective flow-through area that changes as the valve element deflects. The amount of relative engagement between the valve element and the support element changes as the valve element deflects.
In this way, improved crankcase ventilation flow control may be achieved during a variety of operating conditions, while reducing cost and/or manufacturing complexity.